Robot Design: Draft ver. 1.0

Overview of the Design Requirements:
- The robot can be placed on a manually wheeled cart or in some other way we find suitable.
- Assume that the liver is a sphere with a 10 cm diameter.
- Assume that the force needed to push through the liver is 10 N.
- Orientation of the needle around its own axis is not important.

In other words, points of interest of the robot (an in no particular priority order):
i)  An interchangeable end-effector. A gripper should suffice for this condition.
ii) A proximity/distance sensor to keep track and navigate the needle inside the liver.
iii) A force sensor to puncture the liver wall.

Conditions that are of little importance to our robot:
iv)  Robot base/stand. The robot can sit on a rolling platform with brakes for all we care so we'll begin by designing it as a robot generally sitting from the ground.
v) Orientation of the needle (i.e. the roll, pitch, and yaw angles of the needle tip). Therefore, only the insertion of the needle is the necessary factor to consider for the end-effector.


The minimalist robot with the lowest degree-of-freedoms could be a planar robot that is Revolute-Prismatic (RP) or a Prismatic-Prismatic (PP) robot (I was thinking it would only be a prismatic robot but there has to be some sort of height adjustment). The last degree of freedom should be a prismatic joint, because only a prismatic joint allows the needle to insert into and out of the liver.
From the Project Guidelines in section 1:
a. What is the minimal required number of DOFs to complete the task? 2 DOFs
b. What is the required workspace? Needs to be addressed.
c. What is the estimated speed of each joint (very difficult to do, just guess something that sounds reasonable). Needs to be addressed.

Figure 1: Examples of an RP (left) and PP (right) robot. This would be the most basic robots that will meet the design requirements

The most complex robot that should be considered would be a 5 DOF (degree-of-freedom) robot. Structurally, it would consist of two wrists (a wrist is a couple R-R joint) and a prismatic joint and would work in 3-D.

Figure 2: Examples of the 5 DOF robot (Very poorly drawn, sorry, but it was the quickest way I could get a picture of it up on the blog). The bottom picture is the same as the top, but with GREEN highlights that are links, and RED highlights of the z-direction of each link.

Even though it might be redundant, if time permits we should draw everything in MATLAB using the robotics toolkit. Those figures and illustrations in MATLAB would be great for the slides in our presentation, as well as for our report.

Project Guidelines, section 2: Propose a robot kinematics for the task.
We should probably consider a robot between 2 to 5 DOFs.
What do you guys think?